Surface states modulated exchange interaction in Bi2Se3/thulium iron garnet heterostructures*

We investigate the modulation of magnetic anisotropy of thulium iron garnet (TmIG) films by interfaced Bi 2 Se 3 thin films. High quality epitaxial growth of Bi 2 Se 3 films has been achieved by molecular beam epitaxy on TmIG films. By the method of ferromagnetic resonance, we find that the perpendicular magnetic anisotropy (PMA) of TmIG can be greatly strengthened by the adjacent Bi 2 Se 3 layer. Moreover, the competition between topological surface states and thickness dependent bulk states of Bi 2 Se 3 gives rise to the modulation of PMA of the Bi 2 Se 3 /TmIG heterostructures. The interfacial interaction can be attributed to the enhanced exchange coupling between Fe 3+ ions of TmIG mediated by topological surface electrons of Bi 2 Se 3 .